This study evaluates subjects with fever and/or rash to determine the percentage of those infected by the Zika, Chikungunya, or Dengue virus. The study also compares the clinical signs, symptoms, and lab abnormalities related to each virus, to better specify each virus's characteristics. The study has enrolled subjects in several different cohorts including a febrile rash cohort (attempting to capture acute Zika/Chikungunya/Dengue infection), a household cohort (attempting to capture asymptomatic or minimally symptomatic subjects), and a cohort of those with Guillain Barr). Additionally, two subpopulations of the febrile rash cohort have special follow up. This includes the pregnant population, who will be followed through delivery to determine pregnancy outcomes, and those subjects with neurologic or cognitive manifestations who will be evaluated to determine the spectrum of neurologic disease seen with these diseases. Subjects with Guillain Barr with potential exposure to Zika virus are of special interest given the severity of disease. Subjects with Guillain Barr do not need to have a preceding illness suggestive of Zika or other viruses.